British light-heavyweight Buatsi made a winning yet underwhelming beginning to his career under fresh promotional backing with a unanimous decision over Zach Parker in Manchester.
The Olympic bronze medallist's activity level appeared to earn him a split decision in a competitive 10-round fight at the Co-op Live Arena.
But the challenger landed significant shots, delivering effective individual punches in a contest where the styles never quite clicked, with constant grabbing marring the action.
The officials had it 96-94 to the winner, with the third a even score.
"It wasn't my greatest showing but what do champions do? They succeed," the victor said in the arena as he was met by boos from the spectators.
The Londoner returned to winning ways after his first professional defeat - an memorable fight with his previous opponent in last winter - to secure a 20th pro success.
Various analysts believed Parker, thirty-one, should have been awarded the victory but the contender endured the second defeat of his 28-fight professional journey.
The Champion Secures Victory in Uneventful Encounter
His career development has stalled in recent times through management issues and long spells of lack of fights.
Earlier forecast as the rising talent of the British fight scene, he now stands trying to achieve expectations - perhaps in what feels like a final roll of the dice - under fresh management.
He began cautiously, with neither fighter willing to take risks in a calculated initial rounds.
Parker, whose only previous defeat came at super-middleweight against John Ryder in 2022 after suffering a hand injury during the bout, was making just his second appearance at light-heavyweight.
By the halfway stage, Parker had stayed in contention, making life awkward for Buatsi, who worked behind a tight guard to narrowly win the cleaner stanzas.
The crowd's patience diminished during frequent holding, with Parker slipping to the canvas several times during clinches.
Parker ended stronger, but multiple periods were difficult to score. Although, former world champion the boxing analyst - providing analysis for Dazn - had it particularly wide for the challenger, scoring for Buatsi just only one stanza.
Buatsi advances, but with the caliber of hard hitter Benavidez, and Russian star Dmitry Bivol ruling the division, the journey to titles - based on this performance - still appears challenging.
Hatton Memorial Motivates Local Rivalry Fight
In the supporting bout, Arthur defeated Bradley Rea by close verdict in a excellent all-Manchester battle to secure the European light heavyweight belt.
The arena fell silent for a profoundly moving tribute ahead of the contest as ten bells tolled in honor of the city's native Ricky Hatton, who passed away aged 46 in recently.
It was the first major televised match card in the city since the passing of Hatton. As the last bell disappeared, the quiet transitioned to a chant of "there's just one Ricky Hatton".
The competition within the ring reflected the feeling. Arthur was sent to the canvas by a significant blow directly to the jaw in the second round, getting up unsteadily to his feet on the eight count.
But the red-colored shorts of the fighter soon pressed ahead again. Across the ring, Rea - in rival City blue - was damaged early, significant bruising developing under his orbital area as the pair traded hard punches.
Rea, 27, delivered effective strikes but the champion, thirty-four, responded in kind with powerful upward punches as the pace rarely dropped over twelve rounds.
The victor edged the result with scoring tallies of 114-114, narrow lead and clearer margin, but both fighters were relentless and brave, exactly what their idol the legend stood for.
